<template>
  <div>
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight" />
  </div>
</template>
<script lang="ts">
import { watch, onMounted } from "vue";
export default {
  name: "qrcode",
  props: {
    identifyCode: {
      type: String,
      default: ""
    },
    fontSizeMin: {
      type: Number,
      default: 28
    },
    fontSizeMax: {
      type: Number,
      default: 40
    },
    backgroundColorMin: {
      type: Number,
      default: 180
    },
    backgroundColorMax: {
      type: Number,
      default: 240
    },
    colorMin: {
      type: Number,
      default: 50
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 40
    },
    lineColorMax: {
      type: Number,
      default: 180
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    contentWidth: {
      type: Number,
      default: 140
    },
    contentHeight: {
      type: Number,
      default: 48
    }
  },
  setup(props) {
    // 生成一个随机数
    function randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    }
    // 生成一个随机的颜色
    function randomColor(min, max) {
      const r = randomNum(min, max);
      const g = randomNum(min, max);
      const b = randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    }
    function drawPic() {
      const canvas = document.getElementById("s-canvas");
      const ctx = canvas.getContext("2d");
      ctx.textBaseline = "bottom";
      // 绘制背景
      ctx.fillStyle = randomColor(
        props.backgroundColorMin,
        props.backgroundColorMax
      );
      ctx.fillRect(0, 0, props.contentWidth, props.contentHeight);
      // 绘制文字
      for (let i = 0; i < props.identifyCode.length; i++) {
        drawText(ctx, props.identifyCode[i], i);
      }
      drawLine(ctx);
      drawDot(ctx);
    }
    function drawText(ctx, txt, i) {
      ctx.fillStyle = randomColor(props.colorMin, props.colorMax);
      ctx.font = randomNum(props.fontSizeMin, props.fontSizeMax) + "px SimHei";
      const x =
        (i + 1) * (props.contentWidth / (props.identifyCode.length + 1));
      const y = randomNum(props.fontSizeMax, props.contentHeight - 5);
      const deg = randomNum(-30, 30);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y);
      ctx.rotate((deg * Math.PI) / 270);
      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 270);
      ctx.translate(-x, -y);
    }
    function drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 2; i++) {
        ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax);
        ctx.beginPath();
        ctx.moveTo(
          randomNum(0, props.contentWidth),
          randomNum(0, props.contentHeight)
        );
        ctx.lineTo(
          randomNum(0, props.contentWidth),
          randomNum(0, props.contentHeight)
        );
        ctx.stroke();
      }
    }
    function drawDot(ctx) {
      // 绘制干扰点
      for (let i = 0; i < 20; i++) {
        ctx.fillStyle = randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(
          randomNum(0, props.contentWidth),
          randomNum(0, props.contentHeight),
          1,
          0,
          2 * Math.PI
        );
        ctx.fill();
      }
    }
    watch(props, () => {
      drawPic();
    });

    onMounted(() => {
      drawPic();
    });

    return {
      randomNum,
      randomColor,
      drawPic,
      drawText,
      drawLine,
      drawDot
    };
  }
};
</script>
<style lang="scss" scoped></style>
